Help! Did I just fry the pre-amp?

[TheBassGuy]

Since the door that holds the battery in place broke on my USA SUB Sterling, I wanted to figure out how to replace it. When I figured out what type of battery box is used, I popped in the battery and called it a day. Now a few hours later I connected the bass to play a little, but I get no sound. I checked the battery and to my shock, I put it in the wrong way. Yes, this is possible with the SUB's battery box. I flipped it in the right way, but still I get no sound. Only some very vauge popping. Did I just fry the pre-amp, or is there an easy fix for this?

 

[Rod Trussbroken]

Since the door that holds the battery in place broke on my USA SUB Sterling, I wanted to figure out how to replace it. When I figured out what type of battery box is used, I popped in the battery and called it a day. Now a few hours later I connected the bass to play a little, but I get no sound. I checked the battery and to my shock, I put it in the wrong way. Yes, this is possible with the SUB's battery box. I flipped it in the right way, but still I get no sound. Only some very vauge popping. Did I just fry the pre-amp, or is there an easy fix for this?

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I'm not too sure if a battery box would allow you to clip the battery in the wrong way around but perhaps it's possible if the door is broken. In any event, power is only applied to the preamp when the guitar lead is plugged into your Bass.

The SUB Sterling Basses use an early version of the SR5 preamp. I just looked at the preamp board drawing but can't see any diode protection should the battery be reversed.

How long was the lead connected to your Bass and has the preamp acted like this previously?

 

[TheBassGuy]

Thanks for the reply! The battery box used in the SUB is very similar to the one in the attached picture. The battery goes in both ways. It has been plugged in for about 10 seconds before I unplugged it and swapped the battery. I never had any issues with the pre-amp before. If the pre-amp is fried, is it fixable by changing a capacitor or something, or is this a case of 'deep-fried', where all the components are wrecked?

 

[Golem]

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I'm not too sure if a battery box would allow you to clip the battery in the wrong way around but perhaps it's possible if the door is broken. In any event, power is only applied to the preamp when the guitar lead is plugged into your Bass.

The SUB Sterling Basses use an early version of the SR5 preamp. I just looked at the preamp board drawing but can't see any diode protection should the battery be reversed.

How long was the lead connected to your Bass and has the preamp acted like this previously?

As the picture below shows, the springs in the battery box in my 2004 SUB Sterling lack the assymmetrical nature of most other battery boxes, so theres no distinct resistance to inserting the battery backwards :-(

Also visible is the OEM sticker showing the proper polarity for the battery, so if the sticker is still in place, the main source of error would be misreading markings on the battery itself.

I suppose that CS can address the question of whether the preamp is still available or whether a suitable newer version can be fitted. A SUB Sterling is certainly worth properly repairing. Its the secret low cost version of what later became known as the StingRay Special.

While Im not about to reverse my battery to see what happens, Im thankful for this warning to be extra-extra observant of the markings on my batteries !!!

 

[Rod Trussbroken]

Thanks for the reply! The battery box used in the SUB is very similar to the one in the attached picture. The battery goes in both ways. It has been plugged in for about 10 seconds before I unplugged it and swapped the battery. I never had any issues with the pre-amp before. If the pre-amp is fried, is it fixable by changing a capacitor or something, or is this a case of 'deep-fried', where all the components are wrecked?

View attachment 47268

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It's hard to diagnose over the internet but as you've never had preamp problems until now, then I think you may have zapped the IC chip or perhaps you've disturbed a wire somewhere. I don't think any other components would have been damaged.

Do you have a guitar tech you could take it to. If it's the IC then it's easily replaced. The tech could also insert a small diode in the red battery lead that powers the preamp. It will prevent damage should the battery be inserted incorrectly.

If a new preamp is needed, then contacting Customer Service is the way to go. Let us know how it all turns out.

 

[TheBassGuy]

Good to know, thanks! Is there a schematic of this pre-amp? I've searched the internet, but I'm not quite sure what the correct schematic is. My dad is a retired electrician, so my hope is that he can figure it out.

 

[Rod Trussbroken]

Good to know, thanks! Is there a schematic of this pre-amp? I've searched the internet, but I'm not quite sure what the correct schematic is. My dad is a retired electrician, so my hope is that he can figure it out.

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The IC is a "TL062". You can also buy a socket for it. Saves desoldering and resoldering if it needs replacing again.

Contact Customer Service for the schematic. Also tell them about what happened with your Bass. The problem may be something else completely:
[email protected]

 

[nhbassguitar]

Hopefully the preamp circuit includes diode protection against reverse polarity. Sad to say, though, the symptoms point to that not being the case. The schematic will supply the answer.